Electrooptical device, method of manufacturing the same, and electronic equipment

ABSTRACT

An AMLCD having high fineness and high contrast is realized. First, an interlayer film is provided on an element electrode, and an opening portion is formed in the interlayer film. Next, after a first metal layer is formed, an embedded insulating layer is formed. The embedded insulating layer is retreated by a means, such as an etch back method, to realize a state in which only the opening portion is filled with the embedded insulating layer. By this, electric connection between the element electrode and a second metal layer becomes possible while keeping the flatness.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electrooptical device (particularly,a reflection type liquid crystal display device), and more particularlyto a structure of each of a plurality of pixel electrodes provided in apixel matrix circuit in the electrooptical device.

2. Description of the Related Art

In recent years, a technique for manufacturing a TFT on an inexpensiveglass substrate has been rapidly developed. The reason is that thedemand for an AMLCD (Active Matrix Liquid Crystal Display) has beenincreased.

In the AMLCD, a thin film transistor (TFT) as a switching element isdisposed for each of several tens to several millions of pixels arrangedin matrix, and an electric charge going in and out of each of pixelelectrodes is controlled by a switching function of the TFT.

A liquid crystal is put between the respective pixel electrodes and anopposite electrode, and a kind of capacitor is formed. Thus, if anelectric charge going in and out of the capacitor is controlled by theTFT, electrooptical characteristics of the liquid crystal are changedand light passing through a liquid crystal panel is controlled, so thatpicture display can be made.

As a phenomenon peculiar to a display device using such a liquidcrystal, there is a phenomenon called disclination. Although the liquidcrystal is arranged between the pixel electrode and the oppositeelectrode, with orientation having some regularity, there is a casewhere the orientation is disturbed by poor rubbing due to the asperitiesof the surface of the electrode. In this case, the function as a normaloptical shutter is lost at that portion, and poor display, such as lightleak, is caused.

Conventionally, although means, such as a structure of covering a TFTwith a flattened film, have been contrived to prevent the disclination,the means do not necessarily become fundamental solutions. This isbecause even if a flattened film is used, it is impossible to flatten adifference in level at a contact portion of a finally formed pixelelectrode.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing problems,and provides a technique relating to the structure of a contact portionto form a completely flat conductive layer. Particularly, an object ofthe present invention is to completely flatten a pixel electrode of anAMLCD and to prevent the occurrence of disclination caused from adifference in level at a contact portion. Then the area of a requiredblack mask is decreased, so that an effective pixel area is enlarged andan AMLCD with high fineness and high contrast is realized.

According to an aspect of the present invention, an electroopticaldevice comprises a pixel matrix circuit constituted by a plurality ofpixels each including at least one TFT and a pixel electrode connectedto the TFT, and is characterized in that a contact portion forelectrical connection to the TFT is formed at a part of the pixelelectrode, and an insulating layer is embedded in a recess portionformed on the contact portion.

According to another aspect of the present invention, an electroopticaldevice comprises a pixel matrix circuit constituted by a plurality ofpixels each including at least one TFT and a pixel electrode connectedto the TFT, and is characterized in that the pixel electrode is made ofa lamination structure of a first metal layer and a second metal layer,and an insulating layer is put between the first metal layer and thesecond metal layer at a contact portion where the first metal layer isconnected to the TFT.

According to still another aspect of the present invention, anelectrooptical device comprises a pixel matrix circuit constituted by aplurality of pixels each including at least one TFT and a pixelelectrode connected to the TFT, and is characterized in that the pixelelectrode is made of a lamination structure of a first metal layer and asecond metal layer, an insulating film is embedded in a recess portionformed on the first metal layer, and the second metal layer is formed soas to cover the first metal layer and the insulating film.

In the above structure, the first and/or the second metal layer may be asingle layer or a lamination.

The first metal layer may be made of a material selected from Ti(titanium), Cr (chromium), Ta (tantalum), W (tungsten), Mo (molybdenum),Nb (niobium) and Si (silicon).

Further, if the second metal layer is made of a material selected fromAl (aluminum), Cu (copper), Ag (silver), and metal films mainlycontaining those elements, it is possible to form the pixel electrodehaving high reflectivity.

According to still another aspect of the present invention, a method ofmanufacturing an electrooptical device comprises the steps of: formingan opening portion in a first insulating layer; forming a first metallayer so as to cover the first insulating layer and the opening portion;forming a second insulating layer on the first metal layer; etching orpolishing the second insulating layer to make a state where the secondinsulating layer is embedded in only a recess portion formed on thefirst metal layer; and forming a second metal layer so as to cover thefirst metal layer and the embedded second insulating layer.

According to still another aspect of the present invention, a method ofmanufacturing an electrooptical device comprises the steps of: formingan opening portion in a first insulating layer; forming a pixelelectrode so as to cover the first insulating layer and the openingportion; forming a second insulating layer on the pixel electrode; andetching or polishing the second insulating layer to make a state wherethe second insulating layer is embedded in only a recess portion formedon the pixel electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawing;

FIGS. 1A to 1C are views showing formation of a connection structure ofa pixel electrode;

FIGS. 2A to 2D are views showing manufacturing steps of a pixel matrixcircuit;

FIGS. 3A to 3D are views showing manufacturing steps of the pixel matrixcircuit;

FIGS. 4A to 4C are views showing manufacturing steps of the pixel matrixcircuit;

FIGS. 5A to 5C are views showing manufacturing steps of a pixel matrixcircuit;

FIGS. 6A and 6B are views each showing an electrooptical device; and

FIGS. 7A to 7F are views each showing the structure of an electronicequipment.

DETAILED DESCRIPTION OF THE INVENTION

The best mode of carrying out the present invention will be describedwith reference to FIGS. 1A to 1C. In FIG. 1A, reference numeral 100denotes an under film, which may be any of an insulating layer, asemiconductor layer, and a conductive layer. An element electrode(electrode forming a part of a TFT) 101 is patterned on the under film.The element electrode 101 is covered with an interlayer film (interlayerinsulating layer) 102. A single layer or a lamination layer selectedfrom insulating films containing silicon, such as a silicon oxide film,a silicon nitride film, or a silicon nitride oxide film, and an organicresin film is used as the interlayer film 102. Here, an explanation willbe given to a case, as an example, where a single layer of an organicresin film is provided.

After the interlayer film 102 is formed, an opening portion (contacthole) 103 is formed by etching. As a method of etching, both a wetetching method and a dry etching method may be used. It is alsoeffective to improve the coverage of a next formed thin film by making asectional shape of the opening portion 103 taper-shaped. The taperedconfiguration may be achieved by simultaneously etching a photoresistmask during an isotropic etching of the contact hole.

After the opening portion 103 is formed in this way, a first metal layer104 is formed. A material selected from Ti (titanium), Cr (chromium), Ta(tantalum), W (tungsten), Mo (molybdenum), Nb (niobium) and Si (silicon)is used as the metal layer 104. Of course, the first metal layer may bea single layer or a lamination layer. The metal layer serves to makeelectrical connection with the element electrode 101.

After the first metal layer 104 is formed, an embedded insulating layer105 is formed. An organic resin film or an inorganic film is used as theembedded insulating layer 105.

As the organic resin film, a kind of or plural kinds of materialsselected from polyimide, polyamide, polyimide amide, and acryl may beused. Since the films of those materials are formed by a spin coatingmethod, they have merits that covering properties are excellent and thefilm thickness can be easily made thick.

As the inorganic film, it is possible to use a silicon oxide film, asilicon nitride film, a silicon nitride oxide film, or the like. Morepreferably, it is appropriate to use a solution coating type materialcalled SOG (Spin On Glass).

As such a solution coating type material, OCD (Ohka Coating Diffusionsource) made by Tokyo Ohka Industries, Co., Ltd., general silicate glass(PSG, BSG, BPSG), and the like can be enumerated. Since these solutioncoating type materials are also formed by the spin coating method, thesame merits as the organic resin film can be obtained.

After the embedded insulating layer 105 is formed by the spin coatingmethod, a curing step is carried out as the need arises so that asurplus solvent is evaporated and the film quality is improved. Althoughthere are various conditions for the curing step, baking (heattreatment) to a degree of 300° C. and 30 min is necessary.

As another merit of the solution coating type material, it is possibleto cite a feature that coloring is easy. For example, an organic resinfilm blackened by dispersing a carbon-based material has been used as ablack mask. That is, in the present invention, it is also possible toprevent light leak at a contact portion by the embedded insulatinglayer.

When the embedded insulating layer 105 is formed, the state of FIG. 1Ais obtained. After this state is obtained, the embedded insulating layer105 is subjected to an etch back process by a dry etching method so thatan embedded insulating layer 106, which fills only a recess portionformed on the first metal layer 104 through the opening portion 103, isformed (FIG. 1B).

In this etch back step, it is necessary to pay attention to overetchingof the embedded insulating layer 105. That is, in this step, the etchback must be completed at the time when the first metal layer 104 iscompletely exposed in a region other than a contact portion 108 so thatthe surface of the insulating layer 106 is flush with the surface of thefirst metal layer 104. If excessive overetching is carried out, theembedded insulating layer 106 in the opening portion is dug so that adifference in level is produced.

It is also necessary to pay attention to etching conditions. Since theetch back step is carried out by plasma etching, according to etchingconditions, the surface of the first metal layer 104 is roughened. Thiscauses disadvantages, for example, a pixel electrode becomes clouded, sothat this is not preferable. Since the optimum conditions of the plasmaetching become different according to the film quality of the firstinsulating layer and the embedded insulating layer, it is appropriatethat a user suitably determines the conditions.

It is important to use the spin coating method in the formation of theembedded insulating layer 105 on the point that the film thickness canbe easily made thick. In FIG. 1A, the thickness of the embeddedinsulating layer 105 must be made at least comparable with the thicknessof the interlayer film 102 or more than that. Thus, it is possible torealize a throughput much higher than that in the formation by a CVDmethod or a sputtering method.

After the state of FIG. 1B is obtained in this way, a second metal layer107 is formed so as to cover the first metal layer 104 and the embeddedinsulating layer 106, and is patterned. In this way, the elementelectrode 101 is electrically connected to the second metal layer 107(FIG. 1C).

In the contact portion 108, the recess portion formed on the first metallayer 104 is filled with the embedded insulating layer 106. Thus, thesecond metal layer 107 can completely secure the flatness even at thecontact portion 108.

With respect to the present invention having the structure describedabove, the detailed description will be given with embodiments set forthbelow.

[Embodiment 1]

In this embodiment, a method of manufacturing a unit pixel (unit pictureelement) constituting a pixel matrix circuit of an active matrix typeliquid crystal display device driven in a reflection mode will bedescribed with reference to FIGS. 2A to 2D.

First, a quartz substrate 201 as a substrate having an insulatingsurface is prepared. In this embodiment, since a heat treatment at 900to 1100° C. is carried out later, it is necessary to use a materialhaving high heat resistance. Other than the quartz substrate, acrystallized glass (glass ceramic) substrate provided with an underfilm, a silicon substrate provided with a thermal oxidation film, or thelike may be used.

An amorphous silicon film 202 with a thickness of 65 nm is formedthereon, and the amorphous silicon film 202 is crystallized by using atechnique disclosed in Japanese Patent Unexamined Publication No. Hei.8-78329. The technique of the publication is the one for carrying outselective crystallization by using a catalytic element for facilitatingcrystallization. In an alternative, methods disclosed in U.S. patentapplication Ser. No. 08/329,644 (which is issued as U.S. Pat. No.5,643,826) may be used. The entire disclosure of these patents areincorporated herein by reference.

Here, a mask insulating film 203 is formed to selectively add acatalytic element (in this embodiment, nickel) to the amorphous siliconfilm 202. An opening portion 204 is provided in the mask insulating film203.

Then a nickel acetate solution containing nickel of 10 ppm in weight isapplied by a spin coating method to form a catalytic element containinglayer 205.

After the state of FIG. 2A is obtained in this way, a dehydrogenatingstep at 450° C. for one hour is carried out, and then, a heat treatmentat 570° C. for 14 hours is carried out in a nitrogen atmosphere, so thatlateral growth regions 206 are obtained. When the crystallizing step isended in this way, an adding step of phosphorus is carried out bydirectly using the mask insulating film 203 as a mask. A phosphorusadded region 207 is formed by this step.

After the state of FIG. 2B is obtained in this way, a heat treatment at600° C. for 12 hours is carried out, so that nickel remaining in thelateral growth regions 206 is gettered into the phosphorus added region207. In this way, regions (called gettered regions) 208 in which nickelconcentration is lowered to 5×10¹⁷ atoms/cm³ or less, are obtained (FIG.2C).

Next, active layers 209 and 210 made of only the gettered regions 208are formed by patterning. Then a gate insulting film 211 with athickness of 120 nm is formed. The gate insulating film 211 is made of asilicon oxide film, a silicon nitride film, a silicon nitride oxidefilm, or a lamination film of those.

After the gate insulating film 211 is formed in this way, a heattreatment at 950° C. for 30 minutes is carried out in an oxygenatmosphere, so that a thermal oxidation film is formed at an interfacebetween the active layer and the gate insulating film. By doing so, theinterfacial characteristics can be greatly improved.

In the thermal oxidation step, the active layers 209 and 210 are 14oxidized and are thinned. In this embodiment, adjustment is made so thatthe final thickness of the active layer becomes 50 nm. That is, sincethe thickness of the starting film (amorphous silicon film) is 65 nm,oxidation of a film with a thickness of 15 nm is carried out and athermal oxidation film with a thickness of 30 nm is formed (the totalthickness of the gate insulating film becomes 150 nm) (FIG. 2D).

Next, an aluminum film (not shown) containing scandium of 0.2 wt % isformed, and an island-like pattern as an original of a gate electrode isformed by patterning. When the island-like pattern is formed, atechnique disclosed in Japanese Patent Unexamined Publication No. Hei.7-135318 is used. An entire disclosure of U.S. Pat. No. 5,648,277 whichcorresponds to this Japanese patent is incorporated herein by reference.

First, anodic oxidation is carried out in an oxalic acid while a resistmask used in the patterning remains on the above island-like pattern. Atthis time, a forming current of 2 to 3 mV is flown with a platinumelectrode as a cathode, and a reached voltage is made 8 V. In this way,porous anodic oxidation films 212 and 213 are formed.

Thereafter, after the resist mask is removed, anodic oxidation iscarried out in a solution obtained by neutralizing an ethylene glycolsolution containing tartaric acid of 3% with ammonia water. At thistime, it is appropriate that a forming current is made 5 to 6 mV, and areached voltage is made 100 V. In this way, dense nonporous anodicoxidation films 214 and 215 are formed.

Gate electrodes 216 and 217 are defined by the above step. In the pixelmatrix circuit, a gate line for connecting each gate electrode is alsoformed for every line at the same time as the formation of the gateelectrode (FIG. 3A).

Next, the gate insulating film 211 is etched with the gate electrodes216 and 217 as masks. The etching is carried out by a dry etching methodusing a CF₄ gas. By this, gate insulating films having shapes asindicated by 218 and 219 are formed.

In this state, an impurity ion to give one conductivity is added by anion implantation method or a plasma doping method. In this case, if thepixel matrix circuit is constituted by N-type TFTs, it is appropriatethat a P (phosphorus) ion is added, and if the pixel matrix circuit isconstituted by P-type TFTs, it is appropriate that a B (boron) ion isadded.

Incidentally, the above impurity ion adding step is divided into twosteps and is carried out twice. The first adding step is carried outwith a high acceleration voltage of about 80 keV, and adjustment is madeso that the peak of impurity ions comes to a portion under the end(protruding portion) of each of the gate insulating films 218 and 219.The second step is carried out with a low acceleration voltage of about5 keV, and adjustment is made so that impurity ions are not added to theportion under the end (protruding portion) of each of the gateinsulating films 218 and 219.

In this way, source regions 220 and 221, drain regions 222 and 223, lowconcentration impurity regions (also called LDD regions) 224 and 225,and channel formation regions 226 and 227 are formed (FIG. 3B).

At this time, it is preferable to add impurity ions to the source/drainregions to such a degree that the sheet resistance thereof becomes 300to 500 Ω/square. It is necessary to optimize the low concentrationimpurity region according to the performance of a TFT. After the addingstep of impurity ions is ended, a heat treatment is carried out toactivate the impurity ions.

Next, a silicon oxide film with a thickness of 400 nm is formed as afirst interlayer insulating film 228, and source electrodes 229 and 230,and drain electrodes 231 and 232 are formed thereon. In this embodiment,the drain electrode 228 is formed to extend in a pixel.

This is a contrivance for securing capacity as large as possible sincethe drain electrode is used as a lower electrode of an auxiliarycapacitance. Since this embodiment is an example of a reflection type,even the portion under the region where a pixel electrode issubsequently disposed can also be used freely without paying attentionto an opening rate.

After the state of FIG. 3C is obtained in this way, a silicon nitridefilm 233 with a thickness of 50 nm is formed so as to cover thesource/drain electrodes. Then a titanium film 234 as a capacitanceelectrode is formed thereon. In this embodiment, the auxiliarycapacitance is formed between the drain electrode 231 and thecapacitance electrode 234 with the silicon nitride film 233 as adielectric.

Next, an acrylic resin film with a thickness of 1 μm is formed as asecond interlayer insulating film 235. Of course, an organic resin filmof polyimide or the like other than acryl may be used. A black mask 236is formed on the second interlayer insulating film 235.

The black mask 236 has also a function as an electric field shieldingfilm other than a function as a black mask. That is, the black mask hasthe effect to prevent an electric field produced from source/drainwiring lines from affecting a subsequently formed pixel electrode.

After the state of FIG. 3D is obtained in this way, an acrylic resinfilm with a thickness of 1 μm is again formed as a third interlayerinsulating film 237, and opening portions 238 and 239 are formedtherein. Then a titanium film (first metal layer) 240 is formed so as tocover the third interlayer insulating film 237 and the opening portions238 and 239.

Other than the titanium film, a material selected from chromium,tantalum, tungsten, molybdenum, niobium, and silicon (provided thatconductivity is given to silicon) may be used. Moreover, a laminationstructure of materials selected from those elements may be used.

Next, after the titanium film 240 is formed, an acrylic resin film 241with a thickness of 2 μm is formed as an embedded insulating layer. Atthis time, since the acrylic resin film 241 is formed by a spin coatingmethod, it is possible to sufficiently cover the inside of recessportions formed on the first metal layer 240 through the openingportions 238 and 239 (FIG. 4A).

Next, an etch back process is carried out by a dry etching method usingan oxygen gas to etch the acrylic resin film 241. Then a state in whichthe opening portions 238 and 239 are filled with insulating layers 242and 243 is realized (FIG. 4B).

A material (second metal layer) containing aluminum as its mainingredient and having a thickness of 400 nm is formed on the titaniumfilm 240 which is completely flattened by the embedded insulating layers242 and 243, and is patterned, so that pixel electrodes 244 and 245 areformed.

At this time, the titanium film 240 is also patterned continuously. Bydoing so, the respective pixel electrodes can be physically insulatedfrom each other. Although a difference in level, corresponding to thethickness of the two-layered metal layer, occurs at the patterning end,if the difference is disposed over the source electrode 229 or 230, itis eventually shaded with the black mask, so that the difference doesnot cause any problem. Indeed, since the generating position ofdisclination can be fixed to this place, the occurrence of thedifference is advantageous.

In the case where the pixel electrodes are formed in the structure asdescribed above, since the insides of the opening portions 238 and 239are filled with the embedded insulating layers 242 and 243, the pixelelectrodes 244 and 245 can be electrically connected to the drainelectrodes while the flatness of the pixel electrodes is secured. Inthis embodiment, although the material containing aluminum as its mainingredient is used for the pixel electrode, it is also possible to usecopper, silver, or a material containing those as its main ingredient.Other material can be used for the pixel electrode as long as thematerial has a high reflectivity.

It is also acceptable to make such a structure that another conductivefilm (titanium, chromium, tantalum, etc.) is laminated as an under layerof the pixel electrode having such high reflectivity. Since a material,such as aluminum, copper, or silver, has a high reactivity, there isalso a case in which it is better to provide an under film, such as atitanium film, to make an ohmic contact with another conductive film(especially, a silicon film).

The feature of this embodiment exists in that since a difference inlevel does not occur on the pixel electrodes 244 and 245 at the contactportions, the whole surface of the pixel electrode can be effectivelyused. That is, the effective pixel area is enlarged so that autilization efficiency of light is greatly improved.

After the pixel electrodes 244 and 245 are formed in this way, when anorientation film (not shown) is formed thereon, an active matrixsubstrate as one of substrates of a liquid crystal display device iscompleted. Thereafter, an opposite substrate is prepared by a well-knownmeans, and a cell assembling step is performed, so that the activematrix liquid crystal display device is completed.

The thus completed active matrix liquid crystal display device has highbrightness while having high fineness, and picture display having highcontrast can be made.

[Embodiment 2]

In the embodiment 1, although the etch back treatment is carried out tothe embedded conductive layer so that filling of the opening portion iscarried out, it is also possible to carry out a polishing treatmentinstead of the etch back treatment. Typically, it is also by possible toadopt a technique called CMP (Chemical Mechanical Polishing).

In the case where this technique is used, although it is necessary topay attention to the occurrence of dust, if this technique is used,there is no fear of excess overetching in the opening portion. Moreover,since to the first metal layer can function as a polishing stopper,excellent flatness can be realized.

[Embodiment 3]

In this embodiment, a technique for manufacturing a reflection typeAMLCD by a structure different from the embodiment 1 will be describedwith reference to FIGS. 5A to 5C.

First, in accordance with the manufacturing steps of the embodiment 1, athird interlayer insulating film 237 is formed, and an opening portion501 is formed. Then a pixel electrode 502 is formed so as to cover thethird interlayer insulating film 237 and the opening portion 501 (FIG.5A).

Next, an embedded insulating layer 502 having a thickness of 2 μm isformed so as to cover the pixel electrode 502. In this embodiment, apolyimide resin film is used as the embedded insulating layer (FIG. 5B).

Next, the embedded insulating layer 503 is made to retreat (thethickness is made thin), so that an embedded insulating layer 504 isformed in a recess portion formed on the pixel electrode 502 through theopening portion 501. At the same time, an embedded insulating layer 505is formed in a gap between adjacent pixel electrodes. In this way, theflat surface as shown in FIG. 5C is obtained.

If a pigment or carbon-based material (graphite or the like) isdispersed in the embedded insulating layer 503 in advance, it ispossible to color the embedded insulating layers 504 and 505 black.

If the embedded insulating layers 504 and 505 are made light absorbinglayers by dispersing fine particles for coloring in this way, it ispossible to prevent diffused reflection of light at the recess portion,so that a liquid crystal display device having high contrast can be inmanufactured.

Incidentally, it is also possible to carry out the embodiment 2 withrespect to this embodiment.

[Embodiment 4]

In the embodiments 1 to 3, although the explanation has been given witha top gate structure (here, planar type) TFT as an example, even if abottom gate structure (typically, reverse stagger type) TFT is usedinstead of the top gate structure, similar effects can be obtained.

Moreover, the present invention can be applied to not only the TFT butalso to the case where a MOSFET formed on a single crystal silicon waferis used as a pixel switching element.

As described above, the present invention can be applied to a device ofany structure as long as the device is an electrooptical device having apixel electrode. For example, it is possible to use a switching elementof a bottom gate structure and a multi-gate structure in which two thinfilm transistors are connected to a pixel electrode. Moreover, it ispossible to provide an LDD structure a GOLD (gate overlapped lightdrain) structure to the switching element.

[Embodiment 5]

In the electrooptical device set forth in the embodiments 1 to 4, it isalso possible to raise reflectivity by coating the surface of a pixelelectrode with an electrolytic plating.

For example, after a pixel electrode is formed of a material containingaluminum as its main ingredient, anodic oxidation is carried out to forma porous anodic oxidation film on the surface of the electrode. By doingso, the adhesiveness of the plating is raised and the !: pixel electrodehaving very high reflectivity can be realized. As a plating material, itis preferable to use silver having high reflectivity.

If this embodiment is carried out, the kinds of metal films which can beused as pixel electrodes are also greatly increased, and a processmargin is also widened. Moreover, a pixel electrode effectively usingthe reflectivity of silver can be formed at manufacturing cost lessexpensive than the case of using a silver electrode.

[Embodiment 6]

In the embodiments 1 to 5, the explanation has been given with an AMLCDdriven in a reflection mode as an example, it is also possible to applythe present invention to an AMLCD driven in a transmission mode. In thatcase, it is satisfactory if a light transmission window is first securedby changing the arrangement of an auxiliary capacitance and thearrangement of a black mask, and a pixel electrode is made a transparentconductive film (typically ITO).

In the case where a transmission type LCD is manufactured, if a pixelelectrode (transparent conductive film) is made to be directly connectedto an active layer, light leak from a contact portion can become aproblem. Even in such a case, if an embedded insulating layer is coloredso that it has light absorbing properties, the light leak can beeffectively prevented.

[Embodiment 7]

In this embodiment, an example in which an AMLCD is constructed by usingan active matrix substrate (element formation side substrate) having astructure shown in the embodiments 1 to 6, will be described. FIGS. 6Aand 6B respectively show the outer appearance of the AMLCD of thisembodiment.

In FIG. 6A, reference numeral 601 denotes an active matrix substrate onwhich a pixel matrix circuit 602, a source side driving circuit 603, anda gate side driving circuit 604 are formed. It is preferable that thedriving circuit is made of a CMOS circuit in which an N-type TFT and aP-type TFT are complementarily combined. Reference numeral 605 denotesan opposite substrate.

In the AMLCD shown in FIG. 6A, the active matrix substrate 601 and theopposite substrate 605 are bonded to each other in such a manner thattheir respective end faces are flush with each other. However, only somepart of the opposite substrate 605 is removed, and an FPC (FlexiblePrint Circuit) 606 is connected to an exposed portion of the activematrix substrate. An external signal is transmitted to the inside of thecircuit through this FPC 606.

Moreover, IC chips 607 and 608 are attached by using the surface wherethe FPC is attached. These IC chips are structured by forming variouscircuits, such as a processing circuit of a video signal, a timing pulsegenerating circuit, a γ correction circuit, a memory circuit, and anarithmetic circuit, on a silicon substrate. Although two IC chips areattached in FIG. 6A, only one chip or more than two chips may beattached.

The structure as shown in FIG. 6B can also be adopted. In FIG. 6B, thesame portions as those of FIG. 6A are denoted by the same referencenumerals. FIG. 6B shows an example in which signal processing carriedout by the IC chips is carried out by a logic circuit 609 made of TFTson the same substrate. In this case, the logic circuit 609 is also madeof a CMOS circuit as a base like the driving circuits 603 and 604.

Although the AMLCD of this embodiment adopts the structure (BM on TFT)in which a black mask is provided on the active matrix substrate, inaddition to that, it is also possible to make such a structure that ablack mask is provided on the opposite side.

Color display may be made by using a color filter, or a structure notusing a color filter may be adopted by driving a liquid crystal in anECB (Electric field Control Birefringence) mode, GH (Guest Host) mode,or the like.

Like a technique disclosed in Japanese Patent Unexamined Publication No.Hei. 8-15686, a structure using a microlens array may be adopted. Anentire disclosure of this patent is incorporated herein by reference.

[Embodiment 8]

The AMLCD with the structure shown in the embodiments 1 to 7 can be usedfor a display of various electronic equipments. As such electronicequipments, a video camera, a still camera, a projector, a projectionTV, a head mount display, a car navigation system, a personal computer(including a note-sized computer), a portable information terminal(mobile computer, portable telephone, etc.), and the like areenumerated. An example of those is shown in each of FIGS. 7A to 7F.

FIG. 7A shows a portable telephone which is constituted by a main body2001, an audio output portion 2002, an audio input portion 2003, adisplay device 2004, an operation switch 2005, and an antenna 2006. Thepresent invention can be applied to the display device 2004 and thelike.

FIG. 7B shows a video camera which is constituted by a main body 2101, adisplay device 2102, an audio input portion 2103, an operation switch2104, a battery 2105, and an image receiving portion 2106. The presentinvention can be applied to the display device 2102.

FIG. 7C shows a mobile computer which is constituted by a main body2201, a camera portion 2202, an image receiving portion 2203, anoperation switch 2204, and a display device 2205. The present inventioncan be applied to the display device 2205 and the like.

FIG. 7D shows a head mount display which is constituted by a main body2301, a display device 2302, and a band portion 2303. The presentinvention can be applied to the display device 2302.

FIG. 7E shows a rear type projector which is constituted by a main body2401, a light source 2402, a display device 2403, a polarizing beamsplitter 2404, reflectors 2405 and 2406, and a screen 2407. The presentinvention can be applied to the display device 2403.

FIG. 7F shows a front type projector which is constituted by a main body2501, a light source 2502, a display device 2503, an optical system2504, and a screen 2505. The present invention can be applied to thedisplay device 2503.

As described above, the scope of application of the present invention isvery wide, and the present invention can be applied to electronicequipments of any field. Moreover, the present invention can also beeffectively used for a video billboard, a display for advertisement, andthe like.

By carrying out the present invention, it becomes possible to form acompletely flat pixel electrode, and as a result, disclination due to acontact portion (recess portion) of the pixel electrode can beprevented. Thus, an effective display region is greatly enlarged, and itbecomes possible to realize an electrooptical device of higher finenesswith high contrast.

1. A display device comprising a pixel matrix circuit comprising aplurality of pixels each including at least one TFT and a pixelelectrode connected to the TFT, wherein the pixel electrode includes alamination structure of a first metal layer and a second metal layer;wherein the first metal layer is in contact with the second metal layer,an insulating layer is put between the first metal layer and the secondmetal layer at a contact portion where the first metal layer isconnected with the TFT, and wherein the insulating layer comprises alight absorbing layer comprising a resin in which a pigment or acarbon-based material is contained.
 2. A display device according toclaim 1, wherein at least one of the first and the second metal layerhas a single layer structure or a lamination structure.
 3. A displaydevice according to claim 1, wherein the first metal layer is made of amaterial selected from the group consisting of Ti, Cr, Ta, W, Mo, Nb andSi, and the second metal layer is made of a material selected from thegroup consisting of Al, Cu, Ag, and metal films mainly containing thoseelements.
 4. A display device according to claim 1, wherein theinsulating layer is an organic resin film of at least one materialselected from the group consisting of polyimide, polyamide, polyimideamide, and acryl.
 5. An electronic equipment comprising a display deviceaccording to claim 1, as a display.
 6. A display device according toclaim 1 wherein said device is a portable telephone.
 7. A display deviceaccording to claim 1 wherein said device is a video camera.
 8. A displaydevice according to claim 1 wherein said device is a mobile computer. 9.A display device according to claim 1 wherein said device is a rearprojector.
 10. A display device according to claim 1 wherein said deviceis a front projector.
 11. A display device comprising a pixel matrixcircuit comprising: a TFT; a first insulating layer over the TFT,wherein the first insulating layer comprises a contact hole; a firstconductive film over the first insulating film and in the contact hole,wherein the first conductive film is electrically connected to the TFTthrough the contact hole; a second insulating layer filled in thecontact hole, wherein an upper surface of the first conductive filmoutside the contact hole is not covered by the second insulating layer;a second conductive film on and in contact with the upper surface of thefirst conductive film and the second insulating layer, wherein thesecond insulating layer comprises a light absorbing layer comprising aresin in which a pigment or a carbon-based material is contained.
 12. Adisplay device according to claim 11, wherein at least one of the firstand the second metal layer has a single layer structure or a laminationstructure.
 13. A display device according to claim 11, wherein the firstmetal layer is made of a material selected from the group consisting ofTi, Cr, Ta, W, Mo, Nb, and Si, and the second metal layer is made of amaterial selected from the group consisting of Al, Cu, Ag, and metalfilms mainly containing those elements.
 14. A display device accordingto claim 11, wherein the insulating layer is an organic resin film of atleast one material selected from the group consisting of polyamide,polyamide, polyimide amide, and acryl.
 15. An electronic equipmentcomprising a display device according to claim 11, as a display.
 16. Adisplay device according to claim 11 wherein said device is a portabletelephone.
 17. A display device according to claim 11 wherein saiddevice is a video camera.
 18. A display device according to claim 11wherein said device is a mobile computer.
 19. A display device accordingto claim 11 wherein said device is a rear projector.
 20. A displaydevice according to claim 11 wherein said device is a front projector.21. A display device according to claim 11, wherein the first conductivefilm is electrically connected to the TFT through one of a sourceelectrode and a drain electrode thereof.